1 /*
2 * arch/arm/mach-ks8695/time.c
3 *
4 * Copyright (C) 2006 Ben Dooks <ben@simtec.co.uk>
5 * Copyright (C) 2006 Simtec Electronics
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
22 #include <linux/init.h>
23 #include <linux/interrupt.h>
24 #include <linux/irq.h>
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27
28 #include <asm/io.h>
29 #include <asm/mach/time.h>
30
31 #include <asm/arch/regs-timer.h>
32 #include <asm/arch/regs-irq.h>
33
34 #include "generic.h"
35
36 /*
37 * Returns number of ms since last clock interrupt. Note that interrupts
38 * will have been disabled by do_gettimeoffset()
39 */
40 static unsigned long ks8695_gettimeoffset (void)
41 {
42 unsigned long elapsed, tick2, intpending;
43
44 /*
45 * Get the current number of ticks. Note that there is a race
46 * condition between us reading the timer and checking for an
47 * interrupt. We solve this by ensuring that the counter has not
48 * reloaded between our two reads.
49 */
50 elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
51 do {
52 tick2 = elapsed;
53 intpending = __raw_readl(KS8695_IRQ_VA + KS8695_INTST) & (1 << KS8695_IRQ_TIMER1);
54 elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD);
55 } while (elapsed > tick2);
56
57 /* Convert to number of ticks expired (not remaining) */
58 elapsed = (CLOCK_TICK_RATE / HZ) - elapsed;
59
60 /* Is interrupt pending? If so, then timer has been reloaded already. */
61 if (intpending)
62 elapsed += (CLOCK_TICK_RATE / HZ);
63
64 /* Convert ticks to usecs */
65 return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
66 }
67
68 /*
69 * IRQ handler for the timer.
70 */
71 static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id)
72 {
73 timer_tick();
74 return IRQ_HANDLED;
75 }
76
77 static struct irqaction ks8695_timer_irq = {
78 .name = "ks8695_tick",
79 .flags = IRQF_DISABLED | IRQF_TIMER,
80 .handler = ks8695_timer_interrupt,
81 };
82
83 static void ks8695_timer_setup(void)
84 {
85 unsigned long tmout = CLOCK_TICK_RATE / HZ;
86 unsigned long tmcon;
87
88 /* disable timer1 */
89 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
90 __raw_writel(tmcon & ~TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
91
92 __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1TC);
93 __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1PD);
94
95 /* re-enable timer1 */
96 __raw_writel(tmcon | TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON);
97 }
98
99 static void __init ks8695_timer_init (void)
100 {
101 ks8695_timer_setup();
102
103 /* Enable timer interrupts */
104 setup_irq(KS8695_IRQ_TIMER1, &ks8695_timer_irq);
105 }
106
107 struct sys_timer ks8695_timer = {
108 .init = ks8695_timer_init,
109 .offset = ks8695_gettimeoffset,
110 .resume = ks8695_timer_setup,
111 };
112
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